Anyone ever try "power scaling" in an amp?

Bit OT, but I ordered Principles of Power and The Ultimate Tone 1. Principles of Power should be here tomorrow... hope it's not TOO over my head.

 

Actually, my fault, I ordered Principles of Power and Ready Set Go!

 

never tried Power Scaling, although I've known about it for years; I think I've got the kit around here somewhere. If I had to have the best master volume in the world, that's what I'd use, but I rarely have a need for master volume.

just got TUT 5, man, what a wealth of info & designs.

 

See, I don't understand schematics AT ALL. I look at one of those schematics for anything and I'm just completely and 100% baffled. Is there nothing that explains it?

 

Well, can you point me towards something good on how to read schematics? I'm eager to learn...

 

You'll have to wait until TUT4 (to be released later this year I hope) if you want a full on, blow by blow of how power scaling works. It's hinted at in TUT2, and you get a schematic in TUT5. If you can put all the parts together, it's fairly simple to figure out.

I've installed power scaling into a SF Champ and it works great (I have pics and other notes on my blog, which just happens to be down at the moment). In my Champ, PS takes down the wattage from 7 to 0.01W! OK you may be wondering why the heck do you have to install PS in an amp rated for 6W? 6W is still friggin' loud! Maybe not compared to a 100W Marshall, but crank it up and it's still too loud for late night playing. And the max PS setting (lowest power) the cranked tone is still there in spades. So are lots of other tonal shades not possible with the stock amp.

I'll post links once I get everything up and running again.

 

Power Scaling does what it does very well. I've got one of KOC's amps (the London Power Studio) which has PS and it works as advertised. I've also had a PSK kit for over a year, but never gotten around to fitting it into an amp It is harder to fit in some amps (100W plexi) than others (Tweed Deluxe).

For a basic guide to amp circuits (and a step-by-step) walkthough of the schematic of a simple Champ-like amp, have a look at the P1 theory guide at AX84 - http://195.178.239.50/ax84/media/ax84_m35.pdf

The Torres book (Inside Tube Amps?) has a pretty good beginner's explanation, too.

Here's a resistor colour code chart:

 

Check this site http://www.bruceclement.com/music/
under PSK report, it is explained very well.
Darko

 

I think it works great! If I thought for a moment that Power Scaling was flawed or negatively affected the tone I would have never put this technology in our new amplifiers.

Bill

 

Yep...I heard the 50 watt Reeves amp first hand and the awesome thing about it when it was the amp was scaled down the tone was just as sweet at low volumes as it was when it was roaring.

Power scaling is one of thoise things that lets you own a 50 or 100 watt amp and makes it useable in any situation.

-Rich

 

Mojave? I thought I read about this while reading about the Coyote.

 

I've got a London Power Session amp with PS and with certain caveates it works well. The basic theory is that you separate the voltages that run the heaters (stay at 12v), the bias and the B+ (high voltage) power, so that you can adjust them individually. Then you can turn down the B+ without screwing up bias and reduce the amps total output. No way of doing this is going to completely leave the amp's tone alone for two reasons:
1. The Fletcher-Munson curves tell us that the bass and treble are going to sound less distinct as you turn down. This is why your stereo has a loudness switch. This can be partly compensated for by pushing the bass and treble up as you turn down.
2. The power curves aren't exactly the same as you reduce B+.

The net result with my amp is that as I turn down the output the amp starts to sound a little cardboardy. I can compensate with EQ and by reducing the gain, plus Kevin has a new mod that helps, but extremes of reduction do change the sound. To me, the ideal way to reduce power is to combine Power Scaling, inefficient speakers and attenuators so that each contributes 6 dB or so, dropping your total output by 64 times...

 

I use it, kinda sorta. I use an 18W amp on stage, tweak the volumes of the channels to where I like them, put a mic in front of the speaker, and pump it through the PA to fill up the house and run through the monitors. Why would I want to make a 100W amp and run it at 20W? I'd rather take the small amp and make it run louder.

I guess that sounds like a stupid approach, but it works for me.

rooster.

 

Er, if your amp doesn't have Power Scaling installed, you don't actually use it. You're just micing your amp.

As for running a 100W amp at 20W: easy, the tone of that 100W amp cranked up sounds killer, but it will also kill everyone in the audience or get you thrown out (or the cops called if you're at home). You also get greatly increased tube life. It's all explained here:

http://www.londonpower.com/pscaling.htm